1. Field of the Invention
The invention relates to dental implants of the type which include a shaft for insertion into the mandible and/or maxilla.
2. Description of the Prior Art
The dental implant is typically made out of titanium. It is inserted into a precisely drilled socket. New bone will grow up and then interface and adapt to the titanium shaft.
The latest dental implants have shafts which receive a hydroxylapatite coating that permits bone to actually bond thereto. The shafts are generally cylindrical in shape and have various lengths typically from 7 mm to 18 mm to accommodate individual anatomy.
The shaft receives a particular fixed or removable abutment attachment to meet the anatomical limitation requirements of individual patients.
All removable abutments are interchangeable in the shaft. The abutments have inserts with cemented or threaded connections.
Threaded inserts allow for a change of restoration type without disrupting the integrity of the dental implant itself.
Each insert may accept a viscoelastic intramobile element which is intended to absorb and distribute stress, and which imitates the function of the tooth, periodontal ligament, and alveolar bone.
Thus, the restorative dentist or oral surgeon can select from different dental implants systems as alternatives to fixed or removable prosthetics for use in the edentulous or partially edentulous mandible and maxilla. He can choose from endosseous implants which become biointegrated or osseointegrated. These dental implants include those which rely on an accurate press-fit to become established between an uncoated shaft and the surrounding bone, and those which rely on tissue ingrowth into a porous coating on the outer shaft surface. A postoperative mechanical bond is formed between living bone and the coated surface. This bond is known as biointegration.
The coating can also be designed to form a postoperative mechanical biochemical bond with the living bone. This bond is known as osseointegration.
Unfortunately, clinical evidence has shown that the various attempts, at using hard porosities for achieving long-lasting, adequate load transfer and implant stability and fixation, have not been entirely satisfactory because the jaw bone under the shaft tip will increasingly shunt the load from the proximal bone to the distal bone in the region apposite to the shaft tip, and will lead to proximal bone resorption, which tends to reduce the proximal bone's resistance to implant swaying. This tendency further accelerates the bone resorption process, which is unavoidably accompanied by implant instability, great discomfort, and severe pain.
It is an object of this invention to provide different types of dental implants, each having bone resorption preventing means that alleviate the load shunting problem and the resulting proximal bone resorption.